For textile treatment agents and personal care products, perfume components are needed which for an extended period adhere to textile fibres, hair or skin, where they release the fragrance substances of the perfume over an extended period and under controlled conditions. Particularly desirable here are perfume components which do not release their fragrance substances until the user of the personal care product or of the item of clothing treated with the textile treatment agent perspires and unpleasant body odours form due to perspiration. Unpleasant body odours are generally formed through bacteria, which break down the constituents of the sweat. In addition to the formation of unpleasantly smelling compounds, this bacterial degradation also leads to acid degradation products. There is therefore a need for perfume components for textile treatment agents and personal care products which contain fragrance substances in bound form and which release them only under acid conditions, such that an intensified perfume effect can be obtained under these conditions to conceal developing body odours.
Betaine esters of fragrance alcohols are known from WO 6/38528 which can be used in detergents, fabric softeners or cleaning agents and adhere to surfaces such as textile fibres. The fragrance alcohol is released from these betaine esters by hydrolysis, the release of the fragrance alcohol taking place only very slowly under acid conditions. The fragrance alcohol is released from the betaine esters only at pH values of 7 or more.
It is also known from WO 97/36978 that betaine esters of fragrance alcohols are resistant to hydrolysis in the acid range and that the fragrance alcohol is released by hydrolysis only at pH values of over 7.
The betaine esters of fragrance alcohols disclosed in EP-A 1 099 689 are also stable in the acid range.
The same pH-dependence of the stability of betaine esters is also known from DE 35 27 974 for betaine esters used as constituents of hair care products.
Alkoxysilanes are known from U.S. Pat. No. 4,524,018 which contain a fragrance alcohol ROH bonded in the form of an Si—O—R group. The fragrance alcohol is slowly released from these compounds. The document contains no disclosure with regard to the pH-dependence of the release of the fragrance alcohols from the alkoxysilanes and the disclosed alkoxysilanes do not remain adhering to textile fibres, skin or hair because they do not display or cannot develop a positive charge.
EP-A 0 982 023 describes polysiloxanes which contain a fragrance alcohol bonded by means of an Si—O—R group and their use as a constituent of cosmetic preparations. The fragrance alcohol is slowly released from the polysiloxanes in the presence of acetic acid. However, the disclosed polysiloxanes do not display adequate adhesion to surfaces having a negative surface charge, such as textile fibres, skin or hair, since they do not display or cannot develop a positive charge.